Telephone system



June 5, 1928.

R. F. STEHLIK TELEPHONE SYSTEM W www PHT:

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June 5," 1928.

R. F'. sTEHLnK TELEPHONE SYSTEM Jane s, i928,

.1,672,101 R. F. STEHLIK TELEPHONE SYSTEM Fi June 14, 1926 5 Sheets-Sheet 4 June 5, 1928.

R. F. STEHLIK TELEPHONE SYSTEM Filed June 14, 1926 5 Sheets-Sheet Inventur Rnd-allah E' E'lhlk @Mm/.E9

Patented June 5, 1928.

vUNITED STATES- y 1,672,191 PATENT oFFlcE.

RUDOLPH F. STEHLIK, OF CHICAGO, ILLINOIS, SSIGNOR T0 YAUTMA'IIC ELECTRIC VINC., OFOHICAGO, ILLINOIS, A CORPORATION OF DELAWARE.

, vTELEPHONIE! SYSTEM.

Application filed .Tune 14,

The present inventionl relates in general to automatic telephonev Systems, more articularly to such systems in which line 'nders are employed to connect an` idle trunk circuit to a calling line; and the principal object, briefly stated, is the production of av new and improved finder system, in which primary line finders are directed to the con-y tacts of a `calling line, the improvement being. of such a nature as to permit a reduction in the cost oi manufacturing and maintaining of suchequipment without imp'airing its reliability or eiliciencyl y In working out an embodiment ol' this invention, IV employ directive finders of the 100 point type, using switches similar to the well known Strowger connector,l whose wipers are moved-first in a vertical direction' to select the 'desired 'level and then in a horiw z'ontal' direction toy select the desired contacts in that level. Switches of this type have been used for this purpose heretofore;

As a further object ofmy invention I provide the aforementioned finder switch. with a release magnet mechanism which releases the switch whenthe magnetl deenergizes,

rather than when "the magnet energize's as is the common practice. :In carrying out this object I use a release magnet kwhich when energized latches the so called double dog of the switch, and in'addition actuates v certainv spring combinations which produce circuit changes in the finder mechanism. Vhen the release magnet is deenergized its armature withdraws Vthe double dog?? from engagement with the shaft of the switch, permitting `that shaft to restore to normal in the well-known manner.

As a further object of my invention I simplify the finder switch still further by employing a wiper combination which is disengaged vfor the bank contacts during rotation, and which is brought into engage-r ment with the contacts of the' desired line after the wipers have 'been positioned thereon, by energizing' the vertical magnet of the switch. In one embodiment of this object, I employ a yfour contact wiper combination onthe finder', three of the wipers `being spaced away from the contacts during rotation, the iourthor test wiper being in engagement with the contacts over which it passes. When the desired line contacts are reached and tested for busy and found' to be idle,-

1926. serial No. 115,851.

the vertical ymagnet'is energized to yraise the shaft slightly to bring ythe 'remaining wipers of theset into engagement with thev cluded in the circuit of the magnet te which 1 impulses are being lsent by the sender.` Heretoiore revertive control has been accomplished by the provision of contacts operated by the magnet being controlled, those contacts sending a controlling ul'se to the sender when the magnet is fu ly operated. y

In accordance with this object of my invention I make use of the-,gradual rise of current in the magnet, by causing it to induce a *current in the secondary winding of the transformer, that current being vemployed *to maintain" the primary circuit closed.

IVhen the magnet becomes fully energized, the current rise ceases, and the induced current dies away, permitting the sender to'` "openthe magnet circuit to'end they pulse.

'As a further object of my invention, I simplify the sendermechanism by combining the impulse counting and sequence control functions, in such `a manner that they may be performed by one switch which makes one half a revolution per call.v One wiper set of this lswitch is set aside as the sequence switch, that wiper engaging tirst the contacts leading to the vertical magnet of `the' selected finder, andlater to theV rotary magnet of that finder, the other wiper-sof that 'v switch arel the "ordinary impulse counting wipers through which the sender is controlled to position the wipers of Ithe finders upon the contacts lof 'the desired calling line. Further objects not specifically mentioned here, will be apparent 'from the reading of the :detailed specification and claims which follow. f

Referring now to the drawings comprising Figs. 1-5, inclusive, which when arranfred with, Fig. 2 to the right of Fig. l, and fig. 3, below Fig. 1,Fig. 4, below Fig. 2, with the correspondingly numbered lines in alinement, show suiiicient circuit detailsto enable a clear understanding of one embodiment of my invention. Fig. l shows the usual auto- .inatiq subsections aand E, s finder switch F, a secondary switch SS, and a group of relays comprising a part of the contact registration relays.

Fig. 2 shows a selector switch E controllable from a calling substation toiselect a and the sequence-counting switch SQ, which `jointly function to set the finders F upon the contacts of a calling line.

Fig. 5 shows the mechanical details of the .finder switch F, showing particularly the structure of the back acting release mechr4anism.

Referringnow to Fig. 1 in detail, I show two subscribers"substations A and B, Whose numbers in the finder banks are 55 and 31 respectively. Fig. 1, I also show the finder F, which is mechanically similar to the well known Strowger connector, modified slightly in accordance with the objects of this invention. It will be Anoted that the finder F comprises only the vertical and rotary mag nets 104 and 102 respectively and the release magnet 103, that is the finder contains none of the usuall control relays. The release magnet mechanism of the finder F, is mechanically similar to that shown inthe patent of Wilson Lee Campbell, No. 1,582,334 issued April 27, 1926, a structure in which the release armature merely engages the double-dogof the switch when the release magnet is energized, and operates a set of spring contacts to perform functions which will be apparent hereinafter. The wipers o fy the finder F 122 to 124 inclusive, are, with the exceptionv of wiper 123 free from the bank contacts during the time that the rotary magnet rotates the shaft in the selected level. Viper 123 which is `the test wiper engages the line contacts for a purpose which will be apparenthereinafter. In Fig. 1, I also show a secondary switch SS which is mechanically of the wellknown rotary type switch whose wipers have no normal position and move in one direction only as the switch magnet deenergizes'. In the lower right hand corner of Fig. 1, I show a relay group which is a part of the contact marking relay, group through which the. sender is controlled to position the finderl F upon the contacts of the calling line.

Iu Fig.` 2, I show a selector E which is the well-known. Strowger selector switch, whose wipers are elevated under the control of the calling subscriber to select the desired level,

and then rotated automatically under the control of a local testing circuit to select an idle contact set in that level. In Fig. 2, I also show the finder allotter FA through which the nders F are associated with the sender equipment one at a time. Mechanically, the finder allotter FA is similar to the secondary switch SS.

Fig. 3, Ishow the upper portion of the figure the'remainder of the contact marking relay, which together with the relays of Fig. 1 determined the contact designation of the calling lineQ The bottomv of Fig. 3, I show the level marking relays, one of which is energized responsive to a callon one of the lines to mark the level containing that line.

In Fig. 4, I show the sender sequence switch SQ, andthe sender S, through the medium of which the finders are set onto the contact of the calling line. The sender SQ is mechanically similar Vto the finder allotter, and contains wiper 420 which is the sequence wiper, wiper 422 which is the counting wiper, and the wiper 423 4which functions to control the switch-through funcy tion of the sender S. Y

Referring now to Fig. 5, I show the vertical magnets 104 which attract 'armature 503 to engage the teeth of the hub 505, thereby lifting the wiper Carr-ying shaft. The rotary magnet 102 act-uates armature 506 to rotate the shaft. gages thevertical and rotary teeth of the hub 505, to retain vthe shaft in its operated position.l When the. release magnet 103 is energized, armature 502 latches the projection of the double dog 501. lVhen the magnet 103 deenergizes and the armature retracts, the double dog is withdrawn from the hub and the shaft restores. The operation I til) lll)

The double dog 501en4 lUU of this mechanism is explained in more de` tail in the aforementioned patent of Campbell.

Throughout the drawings I have shown a plurality ofbatteries in order to avoid an unnecessary complication. In practicethere would` be but one battery, preferably withy its positive pole grounded.

Assume nowthat the substation A, whose finder number is v55, initiates a call. The removal ofthe receivery will close the circuit first for the fifth level marking relay,kto mark in the banks of the sender switch the fifth vertical Contact so that the finder will be directed to the fifth level. After the fifth level relay is energized, the contact marking relay corresponding with the contacts of the call line, in this case, the fifth contact relay will be energized. to mark the fifth rotary contact in the sender so that the finder will be directed to the fifth contact in thek fifth level. This plan of energizing first the level marking relay and then the contact marking relay prevents the so called scrambling or numbers, that is the energization of the level rel-ay of one calling line land-the contact relayA 'of another call-ing line in case simultaneous calls, a combination, which might direct the finder to the contacts of neither vof the calling lines. y of Vthis case, is similar to that shown in my copending application lSerial No. 733,471' -iled August 22, 1924. y l

The finder allotter FA having previously associated lthe finder F With the sender equipment S, that finder is operated as soon as the level and the contact marking relays are energized. The energization of said latter relay closes a circuit for the start relay of the sender S, that relay energizing to start the in'ipulsing. The eiiergization rof the start relay, closes a circuit from the first grounded level conductor, through Wiper 422, through the impulsing relay. The impulsing relay upon energizing' closes a circuit through the primary Winding of trans-' r former 402 through the Wiper 4120', through the vertical magnet of the finder F. Vertical magnet of ther finder F is highly in-n ductive, andthe current rise therein, will 'be gradual. vDuring the time thatthe current is rising in the vertical magnet, the flux changev in the core of the transformer 402, produced by the current change to theV primary Winding,ivill induce in the secondary of the transformer a proportional voltage. I make use of this induced to drive current through the impulsing relay to maint-ain it energized, that is -I connect the i secondary ofthe transformer through a lock-v ing Winding of the impulsing relay. As long as the current in the` vertical magnet is vbuildin, up, the voltage induced in the secondary of the transformer 402 maintains the impulsing relay energized to keep the` vertical magnet circuit closed. lAssoon as vthe armature of the vertical magnet strikes the core, the inductance of the magnet increases appreciably,and because of this increased inductance, the current through the magnet momentarily remains steady, and thereafter increases at a greatly reduced rate.' Therefore as soon as the vertical magnet armature strikes the core,'the secondary of the transformer loses its voltage because of the momentary falling off of the rate of increase of current in the Winding of the magnet. As soon asthe secondary of the transformer 402 loses its voltage, the

- impulsing relay falls back to end the impulse. Thus it will be seen I have vprovided the new and `pulse control, by meansof which a circuit is maintained closed through thewinding of a magnet until that magnet' is` fully enn e-rgized. As soon asthe armature ofthe fifa magnet strikes the pole piece, there is nothing vto be gained by maintaining the circuit closed through it, and a greatcrspeed of operation can beobtained if the circuit is The register relay arrangement efficient method of revertive.

`openedy at `the inst-aintv that the armature strikes thepole. f. v

, This interaction yof Athe impulsing relay and the transformer in seriesvwith lthe magnet continues as vlong as the Wiper 4:22 of the counter switch finds ground, and afterwhich the switch SQ is rotated idly until the first rotary contact `is encountered. Impulsing relay Aand transformer again function as before, this time v*the transformer being in series with the rotary magnet ofthe. finder instead of the vertical. Vhen the counting Wiper 422 of `the counting switchV SQ losesr ground, the VWipers of the finder F, come to vresa-and the switch SQ idles until the rotary pulsing position is reached, at which time a. circuit is `closed for the rotary magnet vof the finder to energize that magnet to bring the Wipers `into engagement with the desired bank contacts. During the interval in which the sender S is the transmitting impulses to the vertical and rotary magnets of the finder S, the secondary switch SS, Which was started as soon as the start relay Vof the sender Was energized, has

been picking out an idle irst 'selector S, to

which the calling line A is connected as soon as finder Wipers Aare brought into eny gagement with the selective bank contacts.

-As soon asSS connects With E', and F conf nects 'with lthe calling line, the calling subscriber hears Athe vdial tone informing him `that the connection is ready for him to oper- `ate his callingjdevice, 'that operation. being.. old and Well' knoWn'to those skilled in the art. As soon-'Nas the finderv F is Aswitched through, the finder allotter FA,fis stepped olf ofthe contacts leading to F, and is oper- La@ .i maag.

lVhen the subscriber at station A removes his receiver to initiate a call, he iirst coinpletes a circuit for the iifthlevel marking relay 314, that circuit being traceable from ground through the normally closed springs' controlled by relay 429, conductor 188, through springs 136, conductor 195, through springsw120, conductor 160,through` the ca1ling device, receiver, andr transmitter of the station A, conductor 161 throughsprings `121, conductor 18S, through springs 358,

vthroughv the normally closed contacts controlled byspring 376, through the winding of relay 314 to grounded zbattery. Relay 314 energizes over this circuit and at spring 376 and its make contact locks itself to a cir Vcuit traceable from grounded conductor 188 through the winding of relay 309, through the break contact ot springs 364, 367, 370, and 373, through spring 376 and its make contact, through the winding. of relay 314 to grounded battery. vRelay 309 energizes in series with relay 314, operating springs 357 to 362 inclusivefthe former to close a circuit for relays `301, 107 and 108, energizing them n for purposes which will be Vhereinafter pointed out, and the latter, that is, springs 358 to 362 inclusive, opening the circuit of other level marking relays 310 to 313 inclusive, to prevent their energization until the pending call is completed. Springs 357 also closes a circuit for relay 315 which energizes to operate springs 352 to 356, inclusive, to open the circuits of level relays y316 t0 320, to prevent the energization oit' any of those level marking relays until the present call is completed. The energization of relay 314 closes springs 375, therebyclosing a circuit for the fifth contact marking relay `114, that circuit beingtraceable from ground sub-station A, through linefconductor 161,

springs y121, conductor 186, through resistano'e308, to grounded battery, energizing relay 114. It will be noted that the relay 114 was short circuited by ground on conductor 188 back to the relay through springs las, 14.1, .and 15o, man the relay los energized to remove that ground. vThis short .circuiting of the Contact marking relay 114 and the other contact marking relays, prevent the energization of any of those relays until the level marking relay has been fully energized, at which time the circuit is completed only to the level. marking relays corresponding to calling ones of the line whose numbers are in the level represented by the energized level marking relay. Relay 114 upon energizing locks itself over a circuit traceable from grounded spring 134 to the relay 114, spring 150 and its make contact, the break contacts of and the springs 149, 148, 147, 146, to springs 135, through the winding of relay 109 to grounded battery.

Relay 109 energizes operating springs 141 to 145 inclusive to open the circuit of contact marking relays 110 to 113, inclusive, thereby preventing their operation at this time. At springs 151, relay 109 closes a circuit from ground through spring 151, conductor 190 through the winding of relay 302 to grounded battery, energizing that relay to open the springs 336 to 340 inclusive, thereby opening the circuit of marking relays 303 to307 ing elusive, to prevent their energization at this time. With relays 314 and 114 energized, the banks of the counting switch SQ, of the sender are arranged so that the sender will transmit the digit 55. Ground is conducted from springs 377 and its make contact of the relay 314 through the first multiple wire to the fifth Contact in the -lower hand of the bank over which Wiper 422 sweeps. The contacts 1 to 4 of that section yof the bank are also grounded from this same ground through springs 374, 371, 368, 365 and their respective break contacts.

Thus the wiper 222 in traveling.fro1n.con tacts 7 to g encounters five grounded contacts 7 to `j the remainder being ungrounded. Similarly contacts 71. to la of the second section of the bank over which the wiper 422 sweeps are grounded from ground on spring 156 in its make contact that ground being conducted over conductor 180 to contact k fifth contact in that section of the bank, and' the contacts between 7L andv 7c are grounded through springs 155, 154, 153, 152 and their respective break contacts. Thus when the Wiper 422 travels from contacts L to '11, thel rst tive will be grounded, and the second tive open circuited. The` lenergization of relay 302 closes at springs 341 of its make contact .a circuit :tor the start relay 407 of the sender equipment, that circuit being traceable over the conductor 321 through spring 430 through the winding of the relayto ground ed battery. Relayr 407k upon energizing starts the sending mechanismthrough its cycle of operation uponthe contacts of the 'calling line.

Returning now to the energization of relay 107, which closes at springs 133 a circuit traceable over conductor 187 through the winding of slow to pull up relay 404 to grounded battery. Relay 404, delays in operating suficiently long to permit start relay 407 to energize lirst'. When relay 404 energizes, it operates springs 429, to remove the permanent ground from conductor l188 and to substitute therefor ground through spring 435 and-itsmake contact, through spring 429 and its make contact to the conductor 188. The springs 435 being controlled by the relay 407, can subsequently remove ground from conductor-188, to permit the release of relays locked thereto.

Vertical z'mpulsag.

springs 424, conductor 452, springs 437,

. mao-net the voltave induced in the secondar 1 D 7 D Wind-ing ot ltransformer 402, holds relay 403 energized over the circuit includingVv springs 427 and the lower windings, ot transf' former 402 andthe relay 403. Energizer tion of relay 403 closes al circuit from ground through Wiper 423 and the first bank contactv it engages, conductor 454, springs 438, springs '428 and its `makecontact, through the Winding ol' magnet 401 ot the y,sequence f switch SQ, to grounded battery, energizing that magnet preparatory to advancing the Wipers, 42,0 to 423 inclusive, and to open at springs 424 the circuit just traced through the upper Winding of relay 403. Then the vertical magnetis 'fulely energized, there will be no current change to the primary winding of' the transformer 402 and consequently the locking circuit just traced for the relay 40S/WillV be Withoutv l voltage, andy since the initial energizing circuit of that relay-is open aty spring 42,4, relay'deenergifzes to end the: pulse.: W'henuelay 403 deenergizes it opens the circuit. of. the vertical magnet, permitting thaty magnetr to iall back preparatory to taking another step. Relay 403y also opens acircuiit, of 'the magnet 401, which deenergizes. and advances the wipers ot'- the switchSQ one' step, that. is to the second bank contact. The circuit for the upper Winding oi? relay4031isnow closed through the second contact engaged by Wiper 422 from -ground on spring 37K and its make contact, through spring 368 and it- S break Contact, that relay energizing to: trans-- mit another pulse to the` vertical magnet.l The operation as just described continues to., five impulses at which time the wipers of' the finder F are standing opposite the fifth level of their bank and at the end of which Wiper 422 isA engaging the sixth bank Contact in the vertical section of its banl{,tha|.t is the contact j. Since relay 314". is energized, spring 377 is against its make contact and contact j is ungrounded as are theremainin-g contacts between j and g. Thecircuit ot, relay 403 is therefore not closed and the vertical magnet receives no further impulses Ak circuit may .110W be traced from groundthrough Wiper 423now engaging the sixth bank contact which is multipled to the conductor 454, springs 438 spring 428 and i e `break Contact, springs 42.5, through the winding of magnet 401 to'battery,energizing 'that magnet: which breaks itsoxvncircuit at the springs 425, deenergizing the. magnet and.

permitting the armature.y to tall backl to ad! Vance thewi erg to inclusive one; step. lVhen t vie armatureof magnet 40l re-` stores, thev circuit yjust traced through the.

magnet is again closed at springs 42.5,Where upon the magnet reenergizes and again inf terrupts its own circuit, 1n a buzzer like manner4 to advance the switch Wipers; This operation continues until Wiper 422y 'engages .contact hat, which time Wiper, 420 has passed the contacts to which verticalimpulsing corr ductor 250 is multipled and isv engaging the.'

contact c to which the rotary impulsing conductor 1251 is multipled, and the sen-der mechanism is, in position to transmit therotary impulses to the finder. Rota/ry 'mpulsmg With the *Wiperl 422i'e`n`gaging contact lL-KJ the circuitis again f closed forv the Vupper winding ofthe relay 403,.y that vcircuit being traceable from ground" spring v 156 and` its make contact through f the break. contacts of springs l152,'to 155" inclusive, the first rotary counting conductor 184,` which,V is'connec'ted to the contact/t, through the .,vviperl y422, springs 424, conductor 45,2, springs 437 to' the upper yWinding of relay 403`v to battery.

vRelay y40? energizesclosing at its sprin s 426 a circuit orthe 'rotary magnet of tie Vfinder F5 traceable from ,that lspring through the upper winding ot' .transformer 402, conductor 450Wip'er 420, now engaging contact c, conductor 251Wipe1237 of the. finder' allotter FA, conductor 111, through. the Winding of rotary. magnet 102,-to grounded battery, energizing that magnet lto advancefthe l ,Wipers of thetinder Fone rotarystepf .Dun` .A ing thetime `the current is lbuilding up iny the rotary magnet, the 4current change through the primary. winding of, the transf 1 Aformer 402.V induces a currentfin, the secondary Winding, that current beingeifectiveto hold relay `402 energized as before, yRelay 403'v againy closes a circuit .thrgugli spring 428. and its make Contact for the Winding.,V

of the Vmagnet 401 ofthe counting switch y SQ. Whenthe magnet 402 of .the iinder F. is fully energized .relay 403 deenergizes permitting the magnet 102 to fall back prepar-y atory to taking lanother step,*and permitting the magnet/401 to fallback to advance the Wipers. 420A *00-423 v'one step. Since conf tacts I1, to lcv by Wiper` 422 are allgrounded,l the above traced circuit to rotary magnet.

will be closed'. While 'the Awiper is passing v overthojse contacts, that isl the rotary mag,- net. `Wild receive five. impulses, and will function to position the wipers of the.iv finder* -F opposite the test contact in the level, in

` this case the fifth contact in the fifth level. of the relay 409. At springs 439, relay 408 rupter 194 tov grounded battery.

When magnet 401 deenergizes after the fifth impulse, wiper 422 moves from contact it to the next contact, that Contact and the remaining contacts between it and the contact z' are unground, so that the circuit for relay' 403 will not be again closed and no more impulses will' be transmitted to the rotary magnet. The local circuit for magnet 401 which has been traced from wiper 423 then the springs 425, will again be closed and the magnet will operate in a buzzer like fashion to advance the wipers until the wiper .423 reaches lthe contact of its bank at which time the switch-through function take place,

provided the secondary switch is in the proper position.

Secondary swztch'searczes for idle selector.

: tor 178, through .the rotary magnet 105 of the secondary switch SS, through the interwipers 128 to 130, of the secondary switch SS, are standing onthe contacts of a 'busy trunk line, wiper" 129 will encounter a grounded contact, closing ashort circuiting path for the upper lwinding of relay 408,.

that circuit beingvtraceablefrom grounded wiper v129, conductor 177 wiper 238 of the swltch FA, conductor 252, springs 433, yspring'440 and its break contact,to the upper winding of relay 408; The upper winding of relay 408 is thus short circuited'and since direct ground is supplied to the magnet 105 over the'circuit just traced that magnet will energize when the interruptor 194 closes the circuit to battery. When 'the in-l terrupter opens the battery circuit, magnet 105 deenergizes and advances the wipers 128 to 130 one step.l This operation continues as long as wiper 129 encounters` grounded contacts. Assuming that the switch E is idle, conductor 175 will not be grounded and when the wiper 129 encounters the contacts of which the conductor 175 is connected, the short circuit will be removed from the upper winding ofrelay 408 and' that relay w-ill energize in series with the magnet 105 when the interrupter 194 again closes ythe battery circuit. Because of the resistance of the upper winding of relay 408, the magnet 105. does not energize this circuit. Relay 408 upon energizing, locks itself over a circuit traceable from ground. to spring 435 and its make contact, springs 441', through the lower winding of relay 408 to grounded battery. The energizationof relay 408, at springs 440, prepares a point in the switch through circuit, the circuit being held open at this time by springs .443

If the' closes a circuit from ground through those springs and conductor 253, wiper. 239, con-\ ductor 172, through the winding of release magnet 103 ofthe finder F, energizing that y magnet which latches the double dog of the The magnet 103 upon energizing of the secondary-switch SS, the ground'on Iconductor 172 traversing that circuit to mark the selector E asl busy, The' energiz'ation of release magnet 103 also closesy a circuit of the groundingy conductor 172 through ,resistance 158, springs 125, resista-nce 157, springs 127, through the windingfof the vertical magnet 104 to battery, but owing to the high value of resistances. 157 and 158 in series,-the ground onfconductorf172 hasnegligible effect upon vertical magnet 104, should that magnet be operating at this time.

Thus it will be seen thatthe energization of relay 408, responsive to the linding of an idle selector by the secondary switchV SS prepares-the finder and control equipment i for the switch through operation, that operation being performed at the time that the sequence switch SQ, places its wiper 423 upon the cont-acts e. f

Switch through. i

.When wiper 423 reachescontact e, a circuit niay be traced from ground, through wiper 423, conductor 453, through Vwinding lll) of relayf409, through resistance442 tov grounded battery, energizing that relay to switch through the iinder, unless the test wiper of the finder has encountered a grounded contact, indicating that the call* ing line has been called by a connector prior to the arrival ofthe finder wipers on its contacts. Relay 409 upon energizing closes a circuit from ground through springs443, springs 440, springs 433, conductor 252, wiper 238, conductor 177, through resistance 157, springs 127, through the winding of vertical magnet 104, to battery, energizing that magnet to-elevate the shaft suiiiciently. tobring wipers 122, 123 and 124'into engagement with contacts 146 to 166, respec-y tively. AThe elevation of wiper 123 into engagement with contact 165vcloses a circuit from ground through lthat wiper and contacts, throughv thewinding of relay 101 to grounded battery, energizing that relay. At springs 120 and 121,v 'relay 101 opens the register relay circuits, permitting the regis-A y ters to restore in the manner subsequently pointed out.' This operation of relay 101 clears the calling line attachments. The grounding of contact 165 by Wiper 123 pro-` tects the calling line fromintrusion by a connector, the grounded private norma-l p rendering it busy to connectors in the well known l-nected through to the first selector 'E manner. Thel calling line 5A is now conover circuitl traceable from ground through transformer Winding 210, through the lower winding of relay v201, springs 232, conductor y176, Wiper k130, wiper 124, engaging contacts 166, line conductor 161, through the telephone to line conductor 160., contact 164, Wiper 122, wiper 128, conductor 174, springs 228, through the. upperwinding of the line relay 201 to grounded battery. The subscriber is apprised of the fact that lie has obtained alirst selector by dial-tone superposed on the above-'circuit through the Winding 210 of the dialtone transformer, that toneinforming them that the-equipment at the central station is in readiness to receive his. directive impulses, and he vproceeds to operate his ,calling` device'to set up the connection he desires. The

operation oi the selectory E responsive to; the actuation-of the subscribers calling device is well known to those skilledin the art and need not be repeatedin detail here, it being sufficient to.. say that the 'lirst series of' impulses dialed by thesubscriberoperate the vertical magnet 2060i the selector' to.- the, level that is determined .by the number'o'f` impulses in the digit. -The selector thenro tates automatically. being driven by the rotary magnet 20.8, coming to rest upon the lirst idle contact in. that level. at which time the. switch through relay 205 energizes and extends the trunk line to the next switch,

tor or a connector, depending upon the size of the exchange.

At' the time that-,the circuit was closed through wiper 423 to the relay 409, a paral-y lel circuit was,V closed from conductor 453, through spring 436 and its` make contact,4 thence over two parallel paths the one through the upperwinding of relay 408 and grounded battery, and the other over conductor 257 through the winding of magnet 209, of the allotter FA, to grounded battery, energizing the relay and thernagnet.V Relay 405.upon energizing opens, at springs 430, a pointin the circuit of start relay 407, permitting thatrelay to fallback atter a slight interval. The energization ofl magnet k209 attracts the armature preparatory to advancing the wipers 236 to 241 inclusive of the allotter FA onto they next bank contact. When relay 407 falls back, it closes its .cirf cuit from grounded conductor 453, through spring 436 and its breakcontact, springs 425, winding' of magnet 401 to grounded battery, energizing this magnet, which .in terrupts its own circuit of springs 125.v and falls back to advance the wipers 420 to 423 into their normal position, as shown in the vb ank drawing. rI'vhe deenergization of relay 407 disconnects ground from conductor 177 of the finder at springs 433, that disconnection ol' ground being Without effect at thev time, since the release relay 202 or' the selector E, has energized, and at spring22l grounded the conductor 17 5, which is connected to conductor through Wiper 129. The energizetion of relay 407 removes ground romcon-` ductor 188 at springs 435, releasing energized relays 309, 314, which` were locked thereto, those relays upon deenergizingin turn unlock relays 114, 107, 301 and 315, therebyv restoring theregister mechanism to normal in readiness for the next call. t The deener gization of relay-407. at springs 431 close the. local testing circuit tor finder allotter FA..

AWhen the magnet 209 has deenergized and advanced the wipers 236 and 241 to the nest contact, Wiper 240 encounters a grounded contact it' thatvnder was busy, closing a circuit from that ground to conductor 25.4, n springs 434, conductorl 256, springs 242, through-the winding'of magnet 209to grounded.battery.v Magnet 209 energizes over` the circuit kand "at springs 242 interrupts its' )wn circuit falling back Ato'l l advance. the Wipers anotherstep. Magnet 2091` Aoperates 1n a buzzer like manner as long asv the wiper 240 encounters grounded con- .tacts,l coming .to rest deenergized upon the irstjungrounded contact, thereby associatingrthe idle nder ywith the sender mechanism. y which may be either another-similar selec- All maar busy.

As was mentioned above the energizationA of release magnet 103 ot' the finderF of springs 126 moves ground from; the conducv tor 179, that conductor, being the all finders busy eonductor,is kmultipled to all of the finders in the group .and if there is another idle finder in the group this removal of ground by `magnet 103 without elect at this time., However, if the finder 'F is the last ,idle finder of the group, springsy 126,11pon removing ground from. the con ductor 179, removes the normal circuit from the lower Winding of relay 407, and permits'that relay to energize as soonas relay` 407 deenergizes, over `a circuit traceable from ground through spring 435 and vits break contact, through the lower Winding of relay 405 to resistance 406 to grounded battery. Relay 405 upon energizshort 'fing opens at. springs 430 a. point in the cirallotter.

wmector called Zine A 'be/:ore F connects with it.

It will be :noted that the contacts of the connector bank associated with the line A are not protected -by the inititation of the call ontliat line until the linder such` as F connects with it and grounds the contact 165 through the wiper 123. It may happen that during the interval between the removal of the receiver from this substation A and the connection of the inder F tothat line, that a connector may extend a call to the station over the normal cables, The connector' will immediately ground the private which is connected to the contact 165, and energize relay 101 to operate springs120 and 121 to remove the attachments from the line so that the connectory may -ring` thereon. Opening springs `120 and 121 at lthis time will not effect the Sender S from directing the iinder F to the contacts of the calling line, since the reg# istration relays are already energized, and locked up independent of the loop circuit. The iinder F arrives on the line A, this ground on contact 165 will traverse the circuit through wiper 123, conductor 170,

wiper 240 of the finder allotter FA, cony ductor 254, spring 231 and its make contact, through the resistance 442 to grounded battery, short circuiting the relay 409, so that when the sequence switch SQ, positions wiper 423 and the contact e, preparatory to switching tlirouglnrelay 409 will not energize, and the finder F will not be switched through. The ground on conductor 453 however, will energize the relay 405, to release the sender S and to cause the finder alloter FA to seek another fiinder'. l/Vlien the linder allotter FA, moves wi pers 238 oii' the contact to which conductor 177 is connected, and moves wiper 239 off the contact of which conductor 172 is connected, the energizing and locking circuits or the release magnet 103 ot the finder F are broken, permitting that magnet to deenergize and withdraw the doubledog Yfrom the shaft, whereupon the finder F restores to normal in the usual manner. The sendei' S restores to normal, the vsequence switch advances its wipers to their normal position, and 'the finder allotter associates the sender S with the next idle' 'finder of the group, and the equipment is in'readiness for handling the neXt call.

Release.

the finder allotter FA, and maintainsV the vertical magnet 104 and the release 4magnet 103 energized.y been completed, andthe subscribers replace their receivers, i the connector removes ground from the conductor 175, whereupon the vertical magnet 104 deenergizes, and

The foregoing deseriptionof one embodi-f" ment of myinventionis'made by way of vexample only, using a` particular type of equipment. I do not wish to be limited by the specific disclosure as there are many inodilications and :adaptations which 'can' be lVhen the conversation'has made by one skilled in the yart without de-v parting from the scope of the invention.`

Having thus described my inventon, what I consider new and desire to have' protectedby Letters Patent, is pointed out in the ap.- pended claims. i s

TWhat is claimed is:`

1.In a telephone system, a. finder switch j having wipers and banks of contacts through which connections are established', 'only one oi' said wipers engaging associated contact-s while it isin motion, subscriber@ lines terminating. in said banks, means for extending connections tok said lines, means responsive to the initiation of a call on one of said lines for positioning saidy inder wipers Opposite the contacts of said calling line, and means .for preventing the establishment of a connection between said wipers and contacts and 'for releasing said operated finder if a` lou connection has been established to said line during the interval between the initiation of said -call and the positioning of said wipers.

2. In a telephone system, a finder switch having wipers and banks of contacts through `which connections are'established, only one of said wipers engaging; associated `contacts while 1t 1s in motion, subscribers lines terminating in said banks, means for extending lIU connections to said lines, means responsive to the initiation of a call on one of said lines for positioningv said finder wipers opposite the contacts of said calling line, means for preventing the 'establishment' oi"A a connection between said wipers and contacts and for releasing said operated finder if a connection has been established'to said line during the interval between theinitiation of saidcall and the positioning ot' said `wipers, and means 'for establishinga connection between said. wipers and contacts if no tion has been established. l

3. In a `telephone system, a group of inder prior connecl switches each having wipe-rs, said finders containing only the magnets for positioning said wipers to establish connection, and means common to said group for controlling the operation of said magnets, first to position said wipers and subsequently to establish a connection through said wipers.

4. In a telephone system, a. finder switch having wipers, switch banks containing contactsthrough which said wipers establish connections, subscriberslines terminating in saidbankcontacts, primary and secondary magnets in said finders, means responsive toa call on one' of said lines to operate said magnetsto move said `Vwipers in ar-primary and v a :secondary direction respectively to position' them before the contacts of said calling line, and meansyfor thenenergizing said f' prima-ry magnetA to :bri-ng l said wipers into engagement `.with .said contact-s.

5. In' a telephone system, av finder switch having` wipers, switch banks containing contacts :through `which said wipers establish connections, subscribers lines terminating 3in1 said bankcontacts, primary and secondary -magnets --in said finders, meanswresponsive vto a call on one-fof said lines-to operate said magnets to move said wipers in aprimary and a -secondary ydirection respectively to position/them before the cont-actsof said calling line, certain of said wipers engaging yselected ones of said' contacts and the re- Vmaining wipersbeing spaced away `from the respective contacts, and means `fork then en- Lergizing said-primary magnet to bring'said remaining wipers into vengagement with'said contacts.

6. In a 'telephone' system, a vfinder switch having wipers, switch banks containing contacts- Vthrough -which said wipers establish connections, subscribers7lines terminating in ysaid zba'nkkcontacts, primary and secondary magnets .in said finders, means responsive "to, a call on oneot` said lines to operate Vsn`1id mag11etsto move said wipers in a primary anda secondary direction respectively to position themy beforethe contacts of said ycalling line, certain of said wipers engaging selected ones of said contacts and thefremain- Ying wipers'beingspaced awa-y'from the respective contacts, and means or then energizing said'primary magnet .to-bring said 'flatter-wipers into .engagement with Athe, re-

spective contacts while-maintaining the c onnectionv between said 'former wipers and l contacts. c

7.,In a telephone system, a 'finder having wipers, primary and secondarymagnetsfor lvpositioning ,terminating 'in-contacts availablev to said said wipers, subscribers lines wipers, a sendergand a sequence switchior controlling it, means responsive to the initiation of a Vcall on' one of said lines for', operating said sender and 'sequence switch -to position said wipers before the contacts of .the calling line, a secondary switch operable to connect said'finder withV an idle trunk line, means controlled by said sender for operating said secondary switch simultaneously with said finder Aand until it connects with an idle; trunk, means responsive to a `further yoperation ofy said sequence switch after said wipers are positioned for ypreparing a` switching circuit through which said finder is brought into connection with said line, meansv for preventing the operation of said yswitching means if said secondary lswitch has not connected with a trunk.

8. In a telephone system, a finder having wipers, primary and secondary magnetsv for positioning lsaid `wipers subscribers 'lines terminating in contacts;available to lsaid wipers, a lsender and al sequence, switch for controllingk it, meansresponsive to thefinitiationv of a call on one of said lines for operating said ysender and sequence switchtol posit-ion said `wipers before the contacts of the calling line, asecondar switch operable to yconnect said finder wit an idle trunk line,

means controlled by said sender for operat- ,c

Ltion said wipersbefore the contactsl o they calling'line', a secondary'switch operable to i" connect said finder withan idle'trunk line,

`means controlled by said sender `or operating said secondary switch simultaneously )with said finde-r and until it connects with an idletrunlnmeans' responsive to a further operation of said sequence'` switch after said wipers are positioned for preparing a switching circuit through which' 'said finder is brought into connection with said' line, means for preventing the rr'ngieration-'of said switching meansv and 'for releasing' said linder, senderv and sequence switch' after a definite interval Vit" said 'secondary switch does not meanwhile connect with a trunk.

10.l In a telephonev system, a! finder having wipers, primary and secondary. magnets for positioningsaid wipers, subscribers 'lines ,terminating inV contacts available to said wipers, a sender and a sequence switch for controlling it', means responsive tothe initilll) aticnot' a call on one of said lines for operatying said sender andi-sequence switch to position said wipers before the contacts of the calling line, ajsecondary switch operable lto Hitt connect said finder with an idle trunk line, means controlled by said sender for operating said secondary switch simultaneously with said finder and until it connects with an idle trunk, a switching relay in said sender, means for preventing the energizing of said relay until said secondary switch has connected with a trunk, and means responsive to a further operation of said sequence switch vafter said wipers have been posiytioned for closing an operating circuit to said switching relay and to a releasing means, said switching means operating to operate said wipers into connection with said contacts if said secondary switch has connected witha trunk and said releasing means operating independent of said switching'relay te release said yequipment after a definite interval. y

11. In a telephone system, a finder having wipers, a secondary switch having wipers, contacts in said switches through which said wipers establish connections, said `finder wipers disengaging said contacts when in motion and said secondary wipers normally engaging its conta-cts, a direct connected link between the wipers of said switches, subscribers lines terminating in said finder switch contacts, trunk lines terminating in said secondary switch contacts,imeans respons-ive to a call on one of said lines for positioning said finder wiper-s opposite the contacts of that line and for simultaneously starting said secondary switch in search of an idle one of said trunk lines, and means operated after said wipers are positioned to bring them into engagement with the selected contacts only if said secondary switch has connected with an idle trunk line.

y12. In a telephone system, a iindenswitch having wipers, switch banks containing contacts through' which said wipers establish connections, subscribers lines terminating in said bank contacts, primary and secondary magnets in said finder operative :to move said wipers in a primary and a secondary direction respectively, a release magnet vin said finder, a detent for retaining said wipers in theA position in which they were last set, an armature for said release magnet, operated to engage said detent when said magnet energizes and to withdraw said detent to release said wipers when said magnet deenergizes, means responsive to a call on one of said lines for operating said primary and secondary magnets to position said wipers before the contacts of that line, means for then energizing said release magnet, means controlled thereby for energizing said primary maghetto bring said wipersinto engagement with said contacts, and means for subsequently deenergizing said release magnet to restore said finder toits normal position.

13. A sender mechanism comprising means for closing a circuitthrough one winding of a control transformer anda magnet in series, and means'controlled by said transformer 'for maintaining said circuit closed while the vcurrent iow in said circuit is increasing and for then opening it.

14. A sending mechanism, a magnet controlled thereby, a relay and a transformer y in said mechanism, a circuit for one winding of said transformer and magnet in series cont-rolled by said relay, a holding circuit for said relay'eiiergized by currentv induced in the secondary windingl of said trans` former bythe current rise in said primary winding, an armature for said magnet at,-

tracted thereto when the magnet lis ener-v gized, said'current rise being arrested when said armature strikes the magnet and said induced voltage being then eliminated to release said relay to open said `first circuit.

15. A sending mechanism` containing a transformer having two windings a magnet, means in said sender operated toa circuit through one winding of said transformer and said magnet, andtransformer controlled means for maintaining said first means operated until said Amagnet becomesl fully relay, a magnet and a circuit therefor com-f pleted by means controlled by said pulsing relay, one winding of said transformer included insaid circuit in series with said magnet, the current in said circuitrising to its maximum value at a rate governed by the inductance of said circuit, a locking'circuit for said relay closed through the second winding of said -transfoimer and energized by the current induced therein by the current rise in said primary winding,l said second winding being decnergized to release said relay open said circuits when said magnet becomes energized fully.

4 18. A sending mechanism, a magnet controlled thereby. means in said sending mechanism for closing a circuit to said magnet,

and means controlled by said magnet over' said circuit for opening said circuit.

19. A sending mechanism, a source of current, a magnet, means lin said sending mechanism for closing a circuit from said'source of current to said magnet, and means con-- ion trolled by the rise of current in said magnet for maintaining said circuit closed.

20. A sending mechanism, a source of current, a magnet, means 1n said sending mechanism for closing a circuit from said sourcer of currenty to said magnet, and means in said circuit controlled by the current flow' in said magnet for first maintaining and then opening said circuit.

21. A sending mechanism, a source of current, a magnet, a relayl in said sending mechmeans for operating said relay to anism,

source of current to close a circuit from said said magnet, and means controlled by the 

